An environment of a broadcasting is changing as a technology progresses and a demand of a viewer changes. Recently, an analog broadcasting is switched to a digital broadcasting, and a broadcast medium is diversified from a terrestrial broadcasting to a cable broadcasting, a satellite broadcasting, an IP-TV service using a high speed communication network, a terrestrial DMB and a satellite DMB.
The digital broadcasting is capable of providing additional services in various filed such as sports, movies, home shoppings and musics because a capacity thereof is four to eight times that of the analog broadcasting. A wide variety of choices for the viewer is also provided since various types of the broadcasting such as the cable broadcasting, the satellite broadcasting, a DMB (Digital Multimedia Broadcasting) and the IP-TV service.
Specifically, a single broadcasting channel has a bandwidth of 6, 7 or 8 MHz. In the analog broadcasting a broadcast program signal, i.e. an analog video signal and an audio signal is transmitted via a carrier signal having the bandwidth of 6, 7 or 8 MHz. therefore, only one broadcast program signal is transmitted via the single broadcasting channel.
However, in the digital broadcasting, the analog video signal and the audio signal are converted to a digital video data and a digital audio data, and the digital video data and the digital audio data are compressed according to an MPEG technology to be transmitted as the broadcast program signal. Therefore, a plurality of broadcast program signals may be multiplexed in the single broadcasting channel to form a plurality of virtual broadcasting channels.
Accordingly, the digital broadcasting is capable of a multi-channel broadcasting by transmitting the plurality of broadcast program signals wherein the digital video data and the digital audio data are multiplexed into the single broadcasting channel contrary to the analog broadcasting wherein only one broadcast program signal is transmitted via the single broadcasting channel.
The digital broadcasting supports multiple resolutions including a HDTV (High Definition Television) supporting an aspect ratio of 16:9 and a high resolution of 1920×1080 or 1280×720, and a SDTV (Standard Definition Television) supporting an aspect ratio of 16:9 or 4:3 and a resolution of 740×480 or 640×480.
Due to the high resolution of the HDTV, a size of the digital video data is large. As a result, only one broadcast program signal may be transmitted per broadcasting channel. In case of the SDTV, four or five broadcast program signals may be transmitted per broadcasting channel since the size of the digital video data is small, thereby allowing the multi-channel broadcasting.
That is, while only one broadcasting is possible per broadcasting channel in the conventional analog broadcasting, multiple broadcastings are transmitted per broadcasting channel for the multi-channel broadcasting by the compression and the multiplexing of the digital data and the viewer selects the broadcasting from the multiple broadcastings.
Addition to the transmission of the conventional broadcast program signal, various data may be broadcasted and an interactivity may be embodied by associating with the communication network in the digital broadcasting environment. The data broadcasting, various data services using the interactivity in particular, is expected to play a major role in propagating the digital broadcasting in view of an easy use by the viewer.
The terrestrial digital broadcasting was initiated in October, 2001 and the satellite digital broadcasting was initiated in March, 2002 in Korea. The cable digital broadcasting and the IP-TV service are also spreading among cable broadcasters and internet service providers. The terrestrial data broadcasting and the satellite data broadcasting were initiated in June, 2002 in Korea. The digital broadcasting for a mobile reception such as a satellite DMB and a terrestrial DMB is also spreading.
FIG. 1 is a block diagram exemplifying a conventional data broadcast system in a digital broadcast.
As shown, the conventional data broadcast system comprises a broadcasting server 110, a content provider server 120, a data provider server 130 and a receiver 140.
The content provider server 120 provides a broadcast content, i.e. the conventional broadcast program to the broadcasting server 110.
The data provider server 130 provides a content for a data broadcasting, i.e. a data content to the broadcasting server 110.
The broadcasting server 110 receives the broadcast content and the data content from the content provider server 120 and the data provider server 130, respectively, multiplexes and converts the same into various broadcasting specification such as ATSC to be transmitted to the receiver 140 through a broadcast network. The broadcast network includes various networks such as a terrestrial broadcast network, a cable broadcast network, a satellite broadcast network, a high speed communication network of the IP-TV service and a DMB network.
In addition, the broadcasting server 110 may receive a feedback signal transmitted from the receiver 140 through a return channel and transmits the feedback signal to the content provider server 120 or the data provider server 130 for the content provider server 120 or the data provider server 130 to carry out a corresponding process. The receiver 140 may also transmit the feedback signal to the content provider server 120 or the data provider server 130 through the return channel. Preferably, the return channel is embodied by a bidirectional communication network.
The return channel refers to a mean for transmitting a feedback of a viewer to the broadcasting server 110, the content provider server 120 or the data provider server 130 and is not limited in a communication method or a communication format.
The receiver 140 receives the broadcast content and the data content from the broadcasting server 110 and provides the contents to the viewer via a signal processing such as an appropriate decoding. For instance, the receiver 140 may be a digital TV or a set-top box in compliance with the terrestrial broadcasting specification such as the ATSC and interactive data broadcasting specification such as DASE in case of the terrestrial digital broadcasting. The receiver 140 may be a set-top box supporting the broadcasting specification such as OpenCable and DVB and a data broadcasting specification suitable for the broadcasting network such as OCAP and MHP in case of the cable broadcasting or the satellite broadcasting. The receiver 140 may be a set-top box or a mobile communication terminal supporting a corresponding data broadcasting specification in case of the IP-TV or the DMB.
The data content is generally transmitted in a carousel format such as a DSM-CC data/object carousel. Since a processing capacity or a storage capacity of the receiver 140 is limited, it is virtually impossible for the receiver 140 to store and execute an entirety of the data content therein. Therefore, the receiver 140 receives the data content transmitted periodically through the broadcasting network and provides the data content as the data broadcasting.
The data application may be configured to display a text data based on a font and may include a control element such as a widget and an image. For instance, the data application may include a button or an icon for selecting a desired data.
The data application is transmitted within a digital broadcast signal. The receiver 140 receives and processes the data application. The receiver 140 transmits the processed data application to a display apparatus (not shown). The display apparatus displays the received data application.
In embodying the data broadcasting, a method wherein the data application itself is transmitted within the digital broadcast signal, and a resource required for executing the data application is transmitted through the return channel may be employed. That is, the resource such as an image data may be received by a communication with an apparatus for storing the resource such as the data provider server 130.
Currently, in the IP-TV service for instance, the data application is transmitted via an IP multicast method. Therefore, an excessive time is required for the data application to load after the viewer selects a data broadcasting channel.
The broadcasting server 110 transmits the data application by dividing the data application into packets similar to a transmission of a broadcasting packet. The receiver 140 receives the packets and combines the packets into the data application. Particularly, a transmission speed of the data application in the IP multicast method is lower than that of a unicast method. In addition, the packets may be lost during the transmission so that the data application cannot be executed.
A video data of a digital broadcast program may be reproduced even when a portion of packets is lost by ignoring the lost packets and using other packets. However, the data application cannot be executed when a portion of the packets thereof is lost. Therefore, the receiver 140 should re-receive an entirety of the data application when an error occurs.
In addition, even after the receiver 140 receives the packets of the data application, the receiver should combine the received packets according to an order thereof. Therefore, a time for combining the packets is additionally required when the data application is executed.
Moreover, even after the packets are combined, the receiver 140 cannot load the data application in a divided fashion but load and execute the entirety of the data application. Therefore, an execution speed is degraded and the resource of the receiver 140 is excessively used.
Further more, even when the receiver 140 receives the resource separately from the data application through the return channel, the receiver 140 should receive the resource via a HTTP communication. Therefore, the receiving speed is degraded.
Due to the above-described drawbacks, 10 to 30 seconds of time is consumed for the receiver 140 to receive and provide the data application to the viewer. Therefore, the conventional method is disadvantageous in that an excessive time is required for the reception and the execution of the data application.